The field of the disclosure relates generally to gas temperature measurement, and more specifically, to methods and a system for measuring gas temperature in harsh environments using an integrated temperature measurement device including a plurality of temperature measurement techniques.
At least some known turbomachines, such as gas turbine engines, include a plurality of rotating turbine blades or buckets and stationary nozzle segments that channel high-temperature fluids, i.e., combustion gases, through the gas turbine engines. Many of these known gas turbine engines include temperature monitoring systems that provide operational temperature data in real time, i.e., at the time of measurement. Measuring gas temperatures in a combusting flame or harsh environment downstream of a combustor, i.e., a hot gas path may include many sources of inaccuracy and non-repeatability. Many of those relate to physical properties of the temperature measurement mechanisms positioned in or proximate to the flow of the hot combustion gases and/or proximate to the high-temperature gas turbine components. Therefore, to overcome the deficiencies of known temperature measurement mechanisms with respect to gas temperature profiles and near-wall temperature measurements in high-temperature and high-pressure environments, gas turbine manufacturers may elect to fabricate, install, and run hot gas components with greater thermal margins to extend the useful service life of such components. Increasing thermal margins typically manifests as increased wall thicknesses and other ruggedizing methods. Such increased ruggedness of those components increases the costs of production and increases a potential for premature reductions in service life due to excessive temperature profiles induced in the walls of the components during operations that typically include large-scale temperature changes, e.g., startups, shutdowns, and load changes.
Rather than incurring such increased costs associated with increasing the thermal margins high-temperature gas turbine components, manufacturers may choose to install independent and redundant temperature measurement devices that use distinct techniques that include thin filament pyrometry (TFP), high temperature thermocouples, and gas sampling probes. Each technique has characteristics that facilitate accurate and reliable temperature measurements. However, each technique also has at least one drawback. For example, thermocouples and probes for point temperature measurements do not account for radiation effects prominent in the hot gas path. Also, due to the low spatial resolution features and the low accuracy associated with measuring boundary layer temperature profiles, these temperature measurement mechanisms do not provide accurate temperature distribution profiles and alternative computational extrapolations and approximations must be used to facilitate spatial-resolution of the temperature profiles, albeit, with some inaccuracies induced by the modeling techniques and approximations used. In addition, due to the high temperatures in the hot gas path, the service life of the thermocouple wires in such high-temperature environments is shortened. Also, the use of any one of the three techniques identified above eventually requires verification of calibration of the associated temperature measurement devices in harsh test environments to facilitate cross-validation during product testing. As such, redundant temperature measurement devices introduce additional hardware requirements and their associated costs into the instrumentation suite for gas turbine engines.